Transmission



Allg. 9, 193g,l ERBAN TRANSMI S S ION Filed May 18, 1937 5 Sheets-Sheet1 Aug. 9, 1938. R. ERBAN TRANSMISSION Filed May 18, 1937 V v IN VENTOR.zf/mrd'raz BY l@ R. ERBAN TRANSMISSION Filed May 18, 1937 s sheets-sheets R7. m MMM d .7m 7. N

Patented Aug. 9, 1938 PATENT OFFICE 2,125,999 TRANSMISSION RichardErban,New York, N. Y.

Application May 18, 1937, Serial No. 143,252, In Great Britain September23, 1935 ,i i 14 claims.

This invention comprises. improvements in or relating to frictiontransmission mechanisms. More' particularly the invention relates to`mecha. nisms ofthe type (shown for example in my U. S.

"-8 Patent 1,750,167) in which transmission rollers are interposedbetween opposed races running in opposite directions. In such mechanismsthe races are often of torio shape; and variations of speed ratio areobtained by so tilting the rollers 10 that the radii of the tracks ofthe rollers on the races are varied.

In transmissions of this type, tilting of a roller cannot readily bebrought about by applying direct tilting force to the roller mounting,because 'l5 the roller tends to maintain itself tangent to` its circulartrack on the race. Also, direct transverse tilting movement of theroller could only be effected by causing its periphery to slide sidewiseon the races; and since the roller is under V the considerable pressurenecessary to permit a substantial torque to be transmitted from one raceto the other, too great a force would be required to eifect such slidingmovement. For these reasons, various means have been provided fortwisting the roller, i. e.,Y pivotally moving the journals of the roller(or otherwise imparting an equivalent movement to the roller) about anaxis passing through thev contact pointsA of the roller with the races,whereupon the roller moves A" on the bias to a new radial `position oneach of the races. Some prior patents have referred to this. initialmovement which is imparted to the roller as inclination but I herein usethe term twisting to distinguish from various other inlg5 clinationswhich are involved in the apparatus. For convenience in discussing thisaction of the roller, we may consider (ci) that theiroller has a mainaxis of rotation (in its journals), about which the roller rotates as itdrives one race in 40 response to motion of the other race, and (b) thatthe journals of the roller have (in effect, atleast). a twisting axisabout which the journals,` for example, (and hence the roller) aretwisted to initiate a change of speed ratio. This twisting .f5 axispasses through the contact points of the roller on the two races.Additionally, means must be provided to place the roller in a tangentialposition on a new track to which `the roller is moved in making a changeof speed ratio. Theoretically, so at least, this could be done byrestoring the roller to a tangential position after it had completed itsbias movement from the old track to the new track. However, it isdesirable to so arrangethe structure that as the roller approaches thenew 55 track, it will swing toward tangentiat position and reach thetangential position as the new track is reached.A Such a feature impartsstability to the ro1l;er, .which prevents the roller from fluctuatingfrom tangential position during the normal operation of thetransmission. Such stability is 6 obtained by incorporating (in effect,at least) in the roller mounting a third axis, which will be referred toas a rocking axis. In operation the roller is movable about this axisto` stabilize itself in a manner which will be discussed later.

In said U. S. Patent 1,750,167, the rocking axis lies in the plane ofthe roller and is perpendicular to the main axis `oi rotation of theroller. Additionally the rocking axis is inclined by an angle of"advance relative to the twisting axis. When a change of speed ratio is.to be effected, the roller is twisted on the twisting axis. Thistemporarily destroys the equilibrium of the roller so that it startsmoving on the bias toward the new track on the race. As the new track isapproached reverse twisting of the roller automatically takes place torestore the roller to tangential position. In effect, this reversetwisting isa pivotal movement about an instantaneous line which passesthrough Ythe contact points of the roller on the two races; but it isachieved by separate movements of the roller on its two perpendicularaxes (the main axis and the rocking axis) which separatemovements'kinematically combine to produce the reverse twisting,

The above described restoring action bears a certain general resemblanceto the stabilization of the suspension of the front wheel of a bicyclein rolling over the ground. The fork of the bicycle, which is attachedto the wheel axle, can be turned upon an axis which is inclined by anangle of advance relative to that diameter of the front wheel whichpasses through the contact point with the ground. As is well known, thebicycle wheel is stable in tending to maintain itself in a forwarddirection, but turning the fork on the inclined axis results in a newdirection of travel being assumed. In this imperfect analogy, the roadsurface corresponds with the surface of the driving toric race of thefriction transmission.

It is necessary in a roller type friction transmission that theAmounting of each roller be stable in the sense above described. If theroller mounting `be unstable, it will result in shimmying or hunting ofthe roller, which is capable of leading to very large, and indeed almostuncontrollable, wrenching forces upon the mechanism. Thus it isdesirable that the roller mounting be stable in maintaining its runningposition in a plane tangential to its track on the races; and

this is true even in a transmission in which rollers are not intended tobe shifted to provide a change of ratio.

A general object of the present invention is to provide an improvedroller transmission of the type above discussed.

Another object of the invention is to provide such a transmission havinga structure which lends itself to manufacture assembly and adjustment ona quantity production basis.

Other objects of the invention are to reduce the cost of rollertransmissions of the type referred ton and to provide a structure whichis not unduly sensitive to manufacturing variations in the sizes andadjustment of parts.

I have found that in transmissions of the type discussed, the rollerwill be stable if the roller mounting requires the roller to always beso positioned that its central plane will cut the tangent plane of itscontact point with the race along a line which, upon swinging of theroller, will move about an instantaneous center lying on the approachside of the contact point. By approach side is meant the side on whichthe race is approaching the contact point. m'

Of course, there are two races; and this condition should preferably bemaintained as to both races. If the condition is fulfilled as to onlyone race, there must be sufcient stability in connection with that raceto more than offset any instability in connection with the other race.

The requirement for stability does not call for a fixed center ofmovement of the contact line of `said two intersecting planes, but onlyfor a center which does not move over to the non-approach side of thecontact point between the race and the roller. This makes it possible tohave a wider variety of specific roller mounting that will be stable;and examples of the best forms now. known to me are disclosed herein.

Figure 1 is a View, partly in elevation and partly in section, showingthe rollers, one race, and associated parts of one embodiment of theinvention. In part the view is diagrammatic.

Figure 2 is a section, taken in general on the line 2-2 of Figure l, andshowing both races.

Figure 3 is a partly diagrammatic detail view, showing one roller andits adjustment means.

Figure 4 illustrates a second form of the invention, and is a sectionthrough one roller and its mounting. l

Figure 5 is a section taken in general on the line 5 5 of Figure 4.

Figure 6 shows the structure of Figure 4 as viewed from the bottom ofFigur-e 4.

Figures 7, 8, 9 and 10 are quasi kinematic diagrams illustrating variousactions of structures embodying the invention.

Referring to Figures 1, 2, and 3, a spider, or carrier I6 has radialarms 20 (three shown) and a hub 22. Rotatably mounted in the hub is ashaft I2, which carries an attached race II. Another race Ill is mountedcoaxially with the race Il and rotatable relatively thereto. Interposedbetween the races are three rollers I5, which serve to transmit powerbetween the races. A device for generating the axial pressure to insureadhesional contact between the rollers and races is to be used, but isnot shown, since such a device is well known in itself and no showing ofit is necessary in order to explain the function of this presentinvention.

The rim of the spider I6 is provided with three lugs Il which are spacedat 120 and serve as a having stems 32 which pass through the lugs II.These stems are fastened by the nuts 39.

Mounted upon the ball 33 is a bearing-element or journal 35 movable inevery direction to a limited extent, and on which the roller I5 isrotatably mounted. This ball-joint permits a tilting movement of thejournal and roller upon it of about 30 to both sides of the middleposition (as indicated by line B-B, Figure 2), whereas in the directionthat is perpendicular to the tilting, it will permit an angling of about10 to each side from the middle position. The middle position Vis shownin Figure l.

The roller is rotatable upon a diagrammatically illustrated journal 36,and this bearing may be constructed in any preferred manner. It may be aball or roller bearing or a plain bushing as shown in the drawings; andif a bushing, it may have an anti-friction coating at 3l. Shoulders36-36 are provided on both sides so as to keep the center of the rollerin the center of the toroidal profile of the races, or, in other wordsto keep the center of the roller coincident with the center of the ball33.

The shoulder 36 located on the inner side of the roller has an extension40, upon which is fastened a pin 4I. This pin slidably pierces a ballI4. The rim of the spider I6 is formed in three places into a circulargroove 45 coaxial with the spider, and these grooves are spaced at about120. The

grooves 45 have a cross section which corresponds to the balls I4, sothat the balls can be guided by these grooves. A control member,consisting of a hub 23 carrying three arms 24 (two shown) is rotatablymounted upon the hub 22 of the spider. Each arm of the control memberends in a spherical cup 25, which corresponds to a ball I4 and pressesthe ball against the groove 45 of the spider I6. One of the arms 24 isprovided with a ball-end 30, which is jointed to a control rod not shownand serves to move the control member over a limited arc, as indicatedin dot-dash lines at a and 3027 in Figure 1. Y

The control member 23-24 is yieldably pressed against the balls I4 by aspring 28, adjustable by a nut 21. It follows from the abovedescription, that the three balls I4 will be accurately and equallyspaced, if the spherical cups 25 are accurately spaced, and that theballs will keep this position with respect to each other while thecontrol member 23-24 is operated. An inspection of Figure 1 shows thateach ball I4 establishes a non-floating point through which the axis ofpin 4I must pass. The pin 4I is fastened through extension to the rollerjournal 35, which is movable about a fixed geometrical center, i. e. thecenter of the ball 33. Therefore, the element 35-36-40 is free to rotateabout an axis A-A, Figure 1, which is determined by the said twocenters, viz., the centers of the balls 33 and I4. This axis is seenfrom a different point of view at C-C Figure 3. It is obvious that thisaxis is inclined with respect to the plane of rotation of the roller,and an inspection of Figure 3 shows, that this axis is also inclinedwith respect to the diameter X-X passing through the contact points ofthe roller with the races Ill--I I. Additionally, this axis is such thatno change in position of it is produced by the bias movement of theroller to a new track on the race.

An inspection of Figure 1 will show further, that a movement of thecontrol element 23-24 by shifting ball 30, for example by moving thislatter to position 30a., will cause a movement of base for theball-pivots 33 carried on posts 34 the balls I4 in a clockwise directionand also cause `the inclined axis to move from the position A-A to theposition A2-A2. Vice versa, a movement of the control member 30 toposition 30h will cause a movement of the inclined axis from A--A toAI-AL The rollers will be twisted accordingly, being turned on the axisX-X.

Due to this twisting, the plane of rotation of each roller will bechanged from a tangent to its circular track about shaft I2; and therace-contacting points of the roller will make a bias movement inwardlyor outwardly under the influence of the rotation of the races. `If thepoint instantaneously in contact with race I0 moves out, the pointinstantaneously in contact with race |I moves in; and viceversa. Due tothe angle of advance of the axis' A-A with respect to axis XX, thetilting movement of the roller will 'progressively diminish the anglewhich the plane `of the roller forms with a tangent to a circle on therace surface until this angleis Zero and lthe roller has reached again aposition of equilibrium. For the inclination shown in the drawings, theproper direction of rotation of that race which is supposed to liebehind the plane of the paper in Figure l is counterclockwise. Thismakes the roller shown in Figure 3 rotate in a "clockwise direction. Foran opposite direction of rotation, the angle which the axis C`C formswith the axis X-X would have to be reversed, so that the axis C-C wouldconverge toward the spider I6 on the left side of the roller I5, whilethe angle between the axis A-A and the plane of the roller (shown inFigure 1) could remain unchanged.

It is obvious from an inspection of Figures l, 2 and 3 that the form ofthe invention shown permits a very simple form of control-elements and aminimum of such parts, so that the possibilities of difficulties throughmanufacturing inaccuracies are limited to only a few parts. Moreover,these parts are of simple design, and can be easily checked.Furthermore, the contacting surfaces of all joints are large, so thatlittle `wear will occur. Lastly, it will be observed,` that my design asshown in Figures 1-3 automatically eliminates all back-lash in thecontrol movement, with the possible exception of the ball I4 upon thepin 4|. This can be held to practically zero, because of the longguiding surface between the pin and theball, while all possible playbetween the balls I4 and the arms of the control member 23--24 is takenup by the spring 28. 'Ihe construction described insures for the reasonsset forth a very accurate alignment of the rollers, or in other words.,a very small difference between the transmission-ratios of theindividual rollers, and the maintenance of this accurate alignment underworking conditions.

The Figures 4-6 show an embodiment of the invention with a rollermounted in a conventional tiltable frame. For the sake of clarity onlyone roller and associated parts are shown, and the races are omitted. Ithas been known to make such a roller mounting by means of a pin withinthe plane of rotation of the roller and having a bearing permittingangling about an axis inclined with respect to the diameter passingthrough the contact points of the roller with the races. In Figure 4,however, the axis about which the roller is free to tilt is inclinedwith respect to its plane of rotation, and this axis is` rather close tothe axis of rotation of the roller. In Figure 4 this axis is designatedas D-D, and it is `marked as E-E in Figure 5, and as F-F in Figure 6.Referring to Figure 4,fthe Vframe `2|2 is tiltable about the pivots 24U,24|); and such tilting movement can be caused by motion imparted toparts 235, 236 which in turn may be connected to a manually operatedmechanism of known design. The fra-me 2|2 carries a pin 220 r lfl()clined with respect to its bore that fits upon the 15 pin 220. A key 228unites the member 222 and the pin 220 for rotation, so that the inclinedaxis D-D Figure 4, or F-F of Figure 6, can move over a limited angle, ofabout in the drawings. The purpose of this arrangement is to make thedevice operative for both directions of Irotation of the races (andconsequently the rollers). The position in which the attened end of thepin 220 is stopped by the plate 24| as shown in Figure 6 corresponds toa rotation of the roller in clockwise direction. For a rotation in theopposite direction, the attened end 22| and the axis F--F would be movedto a position at about right angles thereto.

The member 222 is surrounded by another member 224, which has a boreslidably fitting over the outer diameter of the member 222, and

inclined with respect to the outer cylindrical surface of the member 224in the opposite direction to the inclination provided in the member 222.2535 The arrangement is such that the outer surface of the element 224will be coaxial with the axis of the pin 220, if the two members assumea certain position, as shown in Figure 4.

The outside of the member 224 is closely fitted in the element 2|'6,which is the journal for the rotation of the roller 2|5. The element 216is provided with shoulders 2|`| on each side, and the shoulder on theone side is provided with two stops, forming a slot or recess 233. Ascrew 2,42 engages `this slot and together with the stops on theshoulder prevents the journal 2I6 from having unlimited rotation withthe roller. However, the slot 233 is Wide enough to permit the element2I| to rotate over an angle at least as great `as the angle which isdescribed by the flattened end 22| of the pin 22|), so that the rollerwill upon reversal of its direction of rotation, cause by the frictionin its bearing a similar reversal` and limited rotational movement ofthe parts 2|6-224-222-220 until 22|! is stopped from further rotation byits end 22| and the opening 245 in the plate 24|.

The stop 242-233 is necessary to prevent a tendency of the journal 2 I Eto rotate the member 224 by friction if its movement is unlimited, andthereby cause a tendency of the roller to deviate to one side of itsposition of equilibrium,

Both members 222 and 224 are provided on their axial ends with sphericalsurfaces having a common center, and both are held in their respectiveposition by the spherical surfaces` of washers 229, 229. An inspectionof the drawings will show that a load upon the roller 2I5, actin-g inthe direction of the axis 24|), 240 would tend to move the member 222 inan axial direction along the pin 220 to one side, and the member 224 tothe other side, if they were not held in position by the washers 229. f

Anytilting movement of the frame will causefa relative movement betweenthe members `222 and 224, thereby twisting the roller about an axispassing through the contact pointsof the roller with the races. Thiscauses the roller to tilt and 'change the speed ratio; and the rollerregains its equilibrium by movement analogous to that discussed inconnection with Figures 1 to 3. In both forms, as shown in the Figures1-3 and 4 6 it may be observed that the axis around -Which the rollerswings, or rotates (tilts) until it reaches the new position, is passingthrough the center of the roller. This is not a condition necessary forthe proper functioning of my device. The axis referred to may pass toeither side of the center of the roller, and may even lie entirely onone side of the roller.

Figures '7 and 8 show diagrammatically a roller 3I5 of the previouslyknown type, free to swing about an axis H--l-I in its plane of rotationand inclined relatively to its diameter through the contact points ofthe roller with the races. Only one contact point of the roller 3l5 withone race is shown at 3H. In Figures 7 and 8 the axis I-I--H intersectswith the tangent T8 through the contact point at 3|9.

The stabilization of the roller by this arrangement is shown in Figure7. The direction of rotation of the roller is assumed to be clockwise(Fig. 8). rIhus the race at point 3H moves from right to left in thegure, and the' point 3I9 is on the approach side of the Contact point.If the roller were displaced for any reason about the axis I-I-H roundwhich its mounting moves, thereby moving its contact point 3|? to either3H or 3H, its tangent T8 or T8" at the respective contact point with therace must still go through the point of intersection 3i9. That is, thetangents converge towards the point 3l9. In the displaced position theroller is no longer parallel to the movement of the race surface fromright to left and at either contact point, 3H' or 3H", a force R or Rrespectively, acting perpendicular to the respective tangents T8 or T8will return the roller and its contact point (moving about the axis H-H)toward its neutral position, or position of equilibrium 3H. YIt will beobvious that if the direction of movement of the raceway were reversedthe forces R R" would be reversed and the roller instead of beingreturned would be forced further out of parallelism with the line ofmovement of the raceway. In other words the equilibrium would beunstable.

In Figure 9, the roller is shown with an axis K-K inclined with respectto its plane of rotation in accordance with the present invention, aswell as being inclined'relatively to its diameter through the contactpoint 411 with the raceway. This axis intersects a tangential plane tothe roller, drawn in the contact point 4H, in the point of intersectionM9. But the tangent TI 0 to the roller does not pass through this pointof intersection as the tangent T8 does in Figure 8. It will be observed,that if the roller is rotated about the axis K--K, while keeping theangle between the plane of the roller and the axis constant, the planeof the roller will envelop a cone with the vertex at 4l@ and theposition of the roller relatively to the raceway, as well as itsequilibrium, will be dependent upon the position which the tangentassumes from the contact point 4H to that cone. For relatively smallangles of tilt, any change in the position of the tangentplane at thecontact point M1 will be equally small, and all tangent-planes can berepresented by the tangent-plane of the original contact point.

In Figure 9 thisis the plane of the paper, if the point 4H is supposedto lie in it, and the center lll is supposed to be above it. In thatcase, all tangent lines from the contact points to the cone are tangentsfrom these points to the intersection line of the cone with the plane ofthe paper (or original tangent-plane). This curve is a conic section,and in the case illustrated it is a parabola, indicated by P. Thetangent TH) through the normal contact point 4H touches the parabola inthe point 420, and this point takes the place of point 3I9 of Figure 7.It constitutes an instantaneous center about which the plane of theroller may be regarded as swinging if the roller is displaced about theaxis K-K.

If the roller is displaced so that its contact point moves to 4H or dll,the respective tangents are TIG and TI 0", and it is clear that theywill not go through the point 420, but through the points 420 and 420respectively. In other words, the instantaneous center of movementshifts to these positions as the movement progresses.

The tangents are still converging towards the approach side with respectto the direction of rotation, however, and the return `forces R and Rrespectively set up in the contact points 4H and 4H will drive theroller back to its equilibrium position 4| 1. If the axis K-K (whichcorresponds to the axis A-A of'Figure 1) is moved in a way similar tothat indicated in Figure 1 by the positions AI-AI or A2-A2, then theintersection curve between thecone CO and the tangent-plane will movedue to the movement of the cone CO and the new position of equilibriumof the roller will be that in which the tangent line through its contactpoint to the intersection curve will be at right angles to the radius inthe contact point. Although the curve will change its form somewhat forwider angles of change in inclination, it will be quite similar forsmaller changes) and it will be understood from the drawings that theroller 4|5, or, its contact point 4H will be forced to follow up or down(taken with respect to the drawings, which corresponds to a movementradially inward or outward with respect to the races on which the rollerruns) any movement that the parabola makes whenever the position of thecone CO is changed by shifting the position of the axis K-K.

It will also be seen that the roller will be stable in its new position,as long as the tangents drawn from adjacent contact-points to thecone-intersection-curve are converging toward the advancing side, justso as has been shown for the original position 4H. Since theintersection curve of the cone CO can be found by known geometricalmethods, this explanation gives the means to determine whether or notthe roller will be in stable equilibrium for the selected angles of theaxis K-K and also means to determine in advance to what position theroller will move for a given change in the angle of the axis K-K.

It is apparent that the forms shown in this application are but a fewexamples of the great variety of forms in which the present inventioncan be embodied and carried out. The specification and description givenwill enable anyone skilled in the art to lay out equivalent designs, andto predetermine whether such designs will fulll the intended purpose.

Theinvention comprises the broad idea to journal a roller for free(Within 'a limited angle) rotational or swinging movement about an axiswhich is inclined with respect to its plane of rotation and which may ormay not change such angle `or inclination `during operation o'fthedevice. It will be understood that the ydevice will ordinarily beoperated submerged in assuitable oil l L or other suitable liquid.

In compliance `with the patent statutes, Ihave disclosedxthe best formsin whichI have contemplated applying my invention, but it will beunderstood'that the disclosure .isillustrative 'and not limiting. u .i

What isclaimed is: `1.a friction transmission comprising tori'c racesand rollers therebetween: a carrierfor said rollers; a spherical pivotforeach of said rollers, such Apivot being positioned on the axis ofrotation of the respective roller and supporting a journal upon whichthe roller is freely rotatable; Ia pivotal joint associated with eachjournal; 'means for guiding-eachof said pivotal joints in a circularpath andiamember supported for `limited rotation about the axis ofthetransmission, said member havingequally spaced `radial extensions eachof which .is operatively connected withone of said pivotal joints,`whereby a limited movement of said member will cause the'said pivotal`joints to move simultaneously and each traveling an equal amount in itsrespective circular path.

2. In a friction transmission comprising toric races and rollerstherebetween; a carrier for said rollers; a spherical pivot for each ofsaid rollers, such pivot being positioned on the axis of rotation of therespective roller and supporting a journal upon which the roller isfreely rotatable; a pivotal joint associated with each journal by asliding connection; means forming a circular path common to all saidpivotal joints; and a member supported for limited rotation about theaxis of the transmission, said member having equally spaced radialextensions each of which is operatively connected with one of saidpivotal joints whereby a limited movement of said member will cause thesaid pivotal joints to move simultaneously in their circular pathwithout disturbing the spacing of said extensions.

3. In a friction transmission, a pair of races, a roller interposedbetween them, a carrier for supporting said roller, a journal for saidroller to rotate freely thereon to transmit power from one `race to theother, a pivotal connection between said journal and said carrier, meansconnected to said journal for maintaining a rocking axis for said rollerinclined with respect to the plane of rotation of said roller, and meansto maintain said inclined rocking axis in a predetermined position withrespect to said carrier.

4. In a friction transmission; a pair of races; a roller interposedtherebetween; acarrier for supporting said roller; a journal upon whichsaid and operator operable means to change the predetermined position ofsaid last named pivotal connection.

5. For use in a friction transmission having toric races, Aa roller, acarrier to support said roller, a journal for said roller to rotatethereupon, means to support said journal from said porting means wherebysaid journal is movable with respect to said carrier only about ageometrical axis inclined with respect to the plane of rotation of theroller, means to maintain said inclined axis in a predetermined positionwith respect to said carrier, and manually operable means to change thepredetermined position of said inclined axis at will.

6. For use in a friction transmission having toric races, a roller, acarrier to support said roller, a journal for said roller to freelyrotate thereupon, means connected to said carrier and to said journalestablishing an axis inclined with respect to the plane of rotation ofthe roller around which axis said journal is freely rockable, Y

and means connected to said journal for preventing radial movement ofthe center of said roller with respect to the axis of said transmission.

7. Foruse in a friction transmission of the toric race and roller type,a roller, a carrier, a journal for said roller to freely rotatethereupon, means connected to4 said carrier for` supporting saidjournal, .means including said rst named means for limiting themovability of said journal relative to said vvcarrier to a rockingmovement about an axis inclined with respect to the plane of rotation ofthe roller, said journal and said last named means cooperating tomaintain a predetermined angle of inclination between said rocking axisand said plane of rotation of the roller.

8. In a friction transmission having toric races, a roller, a carrierfor supporting said roller, a journal upon which said roller can freelyrotate, a pivotal joint connecting said journal to said carrier, auniversal joint movable relatively to said journal and operativelyconnected to said carrier and means operatively connecting said twojoints for establishing a geometrical axis passing through said twojoints and inclined with respect to the plane of rotation of the rollerwhereby said journal can rock freely about said inclined axis.

9. In a friction transmission having toric races, a roller, and acarrier to support the same, a journal upon which said roller can freelyrotate, means establishing a rocking axis for said roller, said meansincluding one ball joint in fixed connection with respect to saidjournal and in xed position with respect to said carrier, another balljoint movable in a plane perpendicular to the axis of the races, meansfor hol-ding said last named ball joint in a definite position, and anelement operatively connecting said last named ball joint to saidjournal whereby the movability of said journal is limited to a rockingmovement about the axis passing through both of said ball joints.

10. In a friction transmission having` torio races, a roller, a carrierfor supporting said roller, a journal upon which said roller is free torotate, two universal joints, means for supporting said journal fromsaid two joints rockable about the geometrical axis determined by saidtwo joints, the rst said joint xedly positioned with respect to saidjournal and with respect to said carrier, the second said joint beingmovable, and means for moving said second joint at will along an arcconcentric with the axis of said races.

11. In a friction transmission, torio races, a roller therebetween, acarrier for supporting said roller, a journal upon which said roller isfree to rotate, two universal joints and means for supporting saidjournal from said two joints rockable carrier, means including a portionof said sup'-Y about the geometrical axis determined by said two joints,the first said joint being fixedly positioned with respect to saidjournal and to said carrier, the second said joint being movable, meansforming a predetermined path with respect to said carrier along whichthe second said joint can be moved at will, and operator operable meansfor holding the second said joint in a definite position along saidpath.

12. In a friction transmission having a pair of races, a rollertherebetween, a carrier for supporting said roller, a journal for saidroller to rotate freely thereupon, two universal joints and means forsupporting said journal rockable about the geometrical axis determinedby said two joints, the rst said joint being positioned with its centerupon the axis of rotation of said roller, the second said joint beingpositioned remote from the axis of rotation of the roller and the twojoints being positioned at different distances from the plane ofrotation of the roller.

13. In a friction transmission having a pair of torio races, a rollertherebetween, a carrier to support said roller, a journal for saidroller to rotate thereupon, means to support said journal from saidcarrier including pivoting elements establishing a rocking axis for saidjournal inclined relatively to the plane of rotation of said roller, andmeans to maintain` said rocking axis in a predetermined positionintersecting the tangent plane of the contact point between said rollerand race in a point on the approach side of said plane with respect tothe direction of rotation of the respective race.

14. In a friction transmission having a pair of torio races, a rollertherebetween, a carrier to support said roller, a journal for saidroller to rotate thereupon, means toy support said journal from saidcarrier including pivoting elements establishing a rocking axis for saidjournal inclined relatively to the plane of rotation of said roller,means to maintain said rocking axis in a position intersecting thetangent plane of the Contact point between said roller and race in apoint situated on the approach side of the plane with respect to thedirection of rotation of the respective race and means automaticallyoperative upon reversal of the direction of rotation of the races toshift the rocking axis to a position where the aforesaid rocking'axislocation also exists with the reversed rotation of the races.

RICHARD ERBAN.

